Recognizing that cartilage degradation is an expected consequence of inflammatory and degenerative joint disease and that the proteoglycan and cellular constituents comprising cartilage matrix are antigenic, it is proposed to examine the potential immunopathologic significance of such cartilage components as regards the causation and/or perpetuation of joint inflammation and cartilage destruction. Research embodies (1) characterization of normal articular cartilage proteoglycan antigenicity, (2) documentation of potential humoral and/or cell mediated immune response to such antigens as well as products of chondrocyte synthesis and chondrocyte surface determinants in patients manifesting articular inflammatory and degenerative disorders, (3) determination of the immunopathologic significance of such sensitization as pertains to immunologically mediated proteoglycan degradation and alterations in chondrocyte synthesis and (4) sequential evaluation of immune response to cartilagenous constituents in experimental animal models of articular inflammation and cartilage degeneration.